CN110518654A - The linear shunt circuit and lithium-ions battery group of equalizaing charge and additives for overcharge protection - Google Patents

Abstract

The invention discloses a linear shunt circuit for balanced charging and overcharge protection and a lithium-ion battery pack. The linear shunt circuit for balanced charging and overcharge protection includes: voltage sampling resistor R1, voltage sampling resistor R2, and current limiting resistor R3 , negative feedback shunt adjustment resistor R4 and precision adjustable reference circuit N1; the voltage sampling resistor R1 and voltage sampling resistor R2 connected in parallel between the positive and negative poles of the lithium-ion battery cell after series connection; the current limiting resistor R3 after series connection, The negative feedback shunt adjustment resistor R4 and the precision adjustable reference circuit N1 are connected in parallel between the positive and negative poles of the lithium-ion battery cell; the reference pin R of the precision adjustable reference circuit N1 is connected to the voltage sampling resistor R1 and the voltage sampling resistor R2 The voltage dividing points are connected in series, the cathode pin K is connected to the current limiting resistor R3, and the anode pin A is connected to the negative feedback shunt adjusting resistor R4. The scheme described in the present invention has simple structure, low power consumption, low cost, and is easy for engineering realization.

Description

Linear shunt circuit and Li-ion battery pack for equalizing charge and overcharge protection

technical field

The invention belongs to the technical field of aerospace power controllers, and in particular relates to a linear shunt circuit for equalizing charging and overcharging protection and a lithium-ion battery pack.

Background technique

Lithium-ion battery refers to a secondary battery that relies on Li+ intercalation and deintercalation between two electrodes for charging and discharging. Compared with traditional zinc-silver batteries, cadmium-nickel batteries, and nickel-hydrogen batteries, lithium-ion batteries have the advantages of high energy density, high open circuit voltage, high output power, wide operating temperature range, no memory effect, and fast charge and discharge speed.

At present, in the field of aerospace, lithium-ion batteries have been widely used in satellites, space stations, and deep space exploration to replace traditional zinc-silver batteries, nickel-cadmium batteries, and nickel-hydrogen batteries. The use of lithium-ion batteries greatly reduces the proportion of battery packs in the total weight of the satellite, increases the payload of the satellite system, and is conducive to the optimization and upgrading of satellite functions.

However, when the lithium-ion battery pack is overcharged, the excessively embedded lithium ions will be permanently fixed in the lattice, but only the lithium ions cannot be released, which will affect the service life and cause serious consequences of explosion. Compared with nickel battery packs, lithium-ion batteries are strictly prohibited from overcharging, and an overcharge protection circuit needs to be added to prevent irreversible damage to the battery pack.

The traditional balance manager and overcharge protection circuit need an operational amplifier to amplify the voltage of the lithium-ion battery and compare it with the reference voltage source, and then adjust the shunt current through the duty cycle. The circuit structure is very complicated and the power consumption is large. .

Contents of the invention

The technical solution of the present invention is to overcome the deficiencies of the prior art, and provide a linear shunt circuit and a lithium-ion battery pack for balanced charging and overcharging protection, which have simple structure, low power consumption, low cost, and are easy to implement in engineering.

In order to solve the above technical problems, the present invention discloses a linear shunt circuit for balanced charging and overcharge protection, including: voltage sampling resistor R1, voltage sampling resistor R2, current limiting resistor R3, negative feedback shunt adjusting resistor R4 and precision adjustable Reference circuit N1;

The voltage sampling resistor R1 and the voltage sampling resistor R2 are connected in series, and the voltage sampling resistor R1 and the voltage sampling resistor R2 connected in series are connected in parallel between the positive and negative poles of the lithium-ion battery cell;

The current limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 are connected in series, and the series connected current limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 are connected in parallel to the lithium-ion battery cell Between positive and negative poles;

The reference pin R of the precision adjustable reference circuit N1 is connected to the series voltage dividing point of the voltage sampling resistor R1 and the voltage sampling resistor R2, the cathode pin K is connected to the current limiting resistor R3, and the anode pin A is connected to the negative feedback shunt adjustment resistor R4 connect.

In the above-mentioned linear shunt circuit for balanced charging and overcharge protection, the voltage sampling resistor R1 and the voltage sampling resistor are connected in series with the positive and negative poles of the lithium-ion battery cell to collect the charging voltage U ₀ of the lithium-ion battery cell After the charging voltage is divided in series by the voltage sampling resistor R1 and the voltage sampling resistor R2, it is used as the input voltage U ₁ of the reference pin R of the precision adjustable reference circuit N1.

In the above-mentioned linear shunt circuit for balanced charging and overcharge protection, one end of the current-limiting resistor R3 is connected to the positive pole of the lithium-ion battery cell, and the other end is connected to the cathode pin K of the precision adjustable reference circuit N1, which is used to limit the linearity The maximum current that the shunt circuit can flow through serves as over-current protection and over-shunt protection.

In the above-mentioned linear shunt circuit for balanced charging and overcharge protection, one end of the negative feedback shunt adjustment resistor R4 is connected to the negative pole of the lithium-ion battery cell, and the other end is connected to the anode pin A of the precision adjustable reference circuit N1 for A linear shunt circuit negative feedback loop is provided to realize the linear shunt characteristics when the charging voltage of a lithium-ion battery cell is raised.

In the above-mentioned linear shunt circuit for balanced charging and overcharge protection, the resistance values of the voltage sampling resistor R1 and the voltage sampling resistor R2 meet the following requirements:

By setting the resistance values of the voltage sampling resistor R1 and the voltage sampling resistor R2, when the charging voltage _U0 of the lithium-ion battery cell reaches the preset shunt voltage threshold U _threshold , there is: the reference pin R of the precision adjustable reference circuit N1 The input voltage U1 _is equal to the internal reference voltage Ubase _of the precision adjustable reference circuit N1, and the linear shunt current _Ib =1mA.

In the above linear shunt circuit for balanced charging and overcharge protection, the precision adjustable reference circuit N1 includes: an internal reference voltage source, an internal integrated operational amplifier, an internal integrated triode and two internal integrated diodes; wherein, the internal reference voltage source, It is used to provide an internal reference voltage of 2.5V; the internal integrated operational amplifier, internal integrated triode and two internal integrated diodes are used to realize deep negative feedback and adjust the linear shunt current I _b .

In the above-mentioned linear shunt circuit for balanced charging and overcharge protection, the resistance value of the current limiting resistor R3 meets the following requirements:

By setting the resistance value of the current limiting resistor R3, the maximum value of the linear shunt current I _b can be adjusted to satisfy: (1+10%)I _max ; where, I _max represents the maximum shunt current value required by the task.

In the above-mentioned linear shunt circuit for balanced charging and overcharge protection, the resistance value of the negative feedback shunt adjustment resistor R4 meets the following requirements:

By setting the resistance value of the negative feedback shunt adjustment resistor R4, the slope of the linear shunt current I _b satisfies a linear change.

The invention also discloses a lithium-ion battery pack, comprising: a charging current source, N-section lithium-ion battery cells and N-way linear shunt circuits for equal charging and overcharge protection; wherein, after N-section lithium-ion battery cells are connected in series Connect between the positive and negative poles of the charging current source; a single lithium-ion battery cell is connected in parallel to a linear shunt circuit for equal charging and overcharge protection; N≥2;

Linear shunt circuit for balanced charging and overcharge protection, including: voltage sampling resistor R1, voltage sampling resistor R2, current limiting resistor R3, negative feedback shunt adjusting resistor R4 and precision adjustable reference circuit N1; where, voltage sampling resistor R1 and voltage The sampling resistor R2 is connected in series, and the series connected voltage sampling resistor R1 and voltage sampling resistor R2 are connected in parallel between the positive and negative electrodes of the lithium-ion battery cell; the current limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 connected in series, the current-limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 are connected in parallel between the positive and negative poles of the lithium-ion battery cell; the reference pin R of the precision adjustable reference circuit N1 is connected to The series voltage dividing point of the voltage sampling resistor R1 and the voltage sampling resistor R2 is connected, the cathode pin K is connected to the current limiting resistor R3, and the anode pin A is connected to the negative feedback shunt adjusting resistor R4.

In the above-mentioned lithium-ion storage battery pack, the capacity of the lithium-ion storage battery pack is not greater than 10Ah.

The present invention has the following advantages:

The invention realizes the balanced charging and overcharge protection of the lithium-ion battery pack with very few electronic components, greatly simplifies the circuit design, and the pure analog circuit greatly improves the stability of the circuit, and has low voltage and low power The characteristics of power consumption are easy to realize in engineering.

Description of drawings

Fig. 1 is a schematic circuit structure diagram of a linear shunt circuit for balanced charging and overcharge protection in an embodiment of the present invention;

FIG. 2 is a schematic diagram of a circuit structure of a precision adjustable reference circuit N1 in an embodiment of the present invention;

3 is a schematic diagram of the working principle of a negative feedback shunt adjusting resistor R4 in an embodiment of the present invention;

Fig. 4 is a schematic diagram of a function verification simulation result of a linear shunt circuit for balanced charging and overcharge protection in an embodiment of the present invention;

Fig. 5 is a schematic structural diagram of a lithium-ion battery pack in an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the embodiments disclosed in the present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, in this embodiment, the linear shunt circuit for balanced charging and overcharge protection is used to simultaneously realize the functions of balanced charging and overcharge protection, and may specifically include: voltage sampling resistor R1, voltage sampling resistor R2, current limiting Resistor R3, negative feedback shunt adjustment resistor R4 and precision adjustable reference circuit N1. Among them, the voltage sampling resistor R1 and the voltage sampling resistor R2 are connected in series, and the voltage sampling resistor R1 and the voltage sampling resistor R2 after series connection are connected in parallel between the positive and negative electrodes of the lithium-ion battery cell; the current limiting resistor R3, the negative feedback shunt adjusting resistor R4 is connected in series with the precision adjustable reference circuit N1, and the series-connected current limiting resistor R3, negative feedback shunt adjustment resistor R4 and precision adjustable reference circuit N1 are connected in parallel between the positive and negative poles of the lithium-ion battery cell; the precision adjustable reference circuit The reference pin R of the circuit N1 is connected to the series voltage dividing point of the voltage sampling resistor R1 and the voltage sampling resistor R2, the cathode pin K is connected to the current limiting resistor R3, and the anode pin A is connected to the negative feedback shunt adjusting resistor R4.

In this embodiment, the voltage sampling resistor R1 and the voltage sampling resistor R2 are connected in series with the positive and negative poles of the lithium-ion battery cell to collect the charging voltage U ₀ of the lithium-ion battery cell, and the charging voltage is passed through the voltage sampling resistor After R1 and the voltage sampling resistor R2 are connected in series to divide the voltage, it is used as the input voltage U ₁ of the reference pin R of the precision adjustable reference circuit N1.

In this embodiment, one end of the current-limiting resistor R3 is connected to the positive pole of the lithium-ion battery cell, and the other end is connected to the cathode pin K of the precision adjustable reference circuit N1, which is used to limit the maximum current that the linear shunt circuit can flow through. Current, play over-current protection and over-shunt protection.

In this embodiment, one end of the negative feedback shunt adjustment resistor R4 is connected to the negative pole of the lithium-ion battery cell, and the other end is connected to the anode pin A of the precision adjustable reference circuit N1 to provide a linear shunt circuit negative feedback loop , to realize the linear shunt characteristics when the charging voltage of lithium-ion battery cells is raised.

In this embodiment, as shown in FIG. 2 , the precision adjustable reference circuit N1 may specifically include: an internal reference voltage source, an internal integrated operational amplifier N, an internal integrated transistor V1 , an internal integrated diode D1 and an internal integrated diode D2. Among them, the internal reference voltage source is used to provide an internal reference voltage of 2.5V; the internal integrated operational amplifier, internal integrated triode and two internal integrated diodes are used to realize deep negative feedback and adjust the linear shunt current I _b . Wherein, it should be noted that the precision adjustable reference circuit N1 may use TL431 or similar reference components, which is not limited in this embodiment.

In this embodiment, the resistance values of the voltage sampling resistor R1 and the voltage sampling resistor R2 meet the following requirements:

By setting the resistance values of the voltage sampling resistor R1 and the voltage sampling resistor R2, when the charging voltage _U0 of the lithium-ion battery cell reaches the preset shunt voltage threshold U _threshold , there is: the reference pin R of the precision adjustable reference circuit N1 The input voltage U1 _is equal to the internal reference voltage Ubase _of the precision adjustable reference circuit N1, and the linear shunt current _Ib =1mA. Among them, it should be noted that due to the individual differences of the precision adjustable reference circuit N1, the resistance values of the voltage sampling resistor R1 and the voltage sampling resistor R2 can be adjusted according to the actual situation, so that the linear shunt current at the preset shunt voltage threshold U _threshold is at Around 1mA.

In this embodiment, the resistance value of the current limiting resistor R3 meets the following requirements:

By setting the resistance value of the current-limiting resistor R3, the maximum value of the linear shunt current I _b is adjusted to satisfy: (1+10%) I _max , which plays the role of over-current protection. Among them, I _max represents the maximum shunt current value required by the task.

In this embodiment, the resistance value of the negative feedback shunt adjustment resistor R4 meets the following requirements:

By setting the resistance value of the negative feedback shunt adjustment resistor R4, the slope of the linear shunt current I _b satisfies a linear change.

Among them, it should be noted that, as shown in Figure 3, the principle of negative feedback shunt adjustment resistor R4 providing the circuit negative feedback path to realize linear shunt is as follows: During the charging process of lithium-ion battery cells, the charging current source provides charging current, with the charging process As the process progresses, the charging voltage U ₀ of the lithium-ion battery cell gradually rises, and the sampling voltage (the input voltage U ₁ of the reference pin R of the precision adjustable reference circuit N1) also rises accordingly. When the sampling voltage is lower than the 2.5V reference voltage, the internal integrated operational amplifier of the precision adjustable reference circuit N1 has no output voltage, and the current flowing through the internal integrated transistor V1 of the precision adjustable reference circuit N1 is zero at this time, that is, there is no shunt current. When the sampling voltage reaches the reference point of 2.5V, the output of the internal integrated operational amplifier increases, the current flows through the internal integrated triode, and begins to divide normally. The shunted current will flow through the negative feedback shunt adjustment resistor R4, so the voltage drop on the negative feedback shunt adjustment resistor R4 increases, causing the negative terminal voltage of the internal integrated operational amplifier to be raised, forming a negative feedback mechanism. Based on the principle of deep negative feedback, the voltage at the positive and negative ends of the internal integrated operational amplifier is kept consistent, and the variation of the sampling voltage is the voltage U ₂ on the negative feedback shunt adjustment resistor R4, and the shunt current should be linear.

It can be seen from the above that under normal working conditions, the charging voltage of the lithium-ion battery cells in the lithium-ion battery pack is fixed, and there is a small difference between them. When the charging voltage U ₀ of any lithium-ion battery cell is abnormal When rising, the sampling voltage of the voltage sampling resistor R1 and the voltage sampling resistor R2 connected in series (that is, the input voltage U ₁ of the reference pin R of the precision adjustable reference circuit N1) is raised, and is greater than that of the precision adjustable reference circuit N1 The internal reference voltage U _base , the output voltage of the internal integrated operational amplifier of the precision adjustable reference circuit N1 increases, so that the current flowing through the internal integrated triode of the precision adjustable reference circuit N1 increases, and the precision adjustable reference circuit N1 starts Split the charging current. Under the adjustment of the negative feedback shunt adjustment resistor R4, the linear shunt current I _b is proportional to the variation of the sampling voltage U1 (ie, U ₂ shown in FIG. 1 ). It can be seen that in this embodiment, by shunting the charging current, the abnormal increase of the charging voltage of the lithium-ion battery is limited, the balanced charging is realized and overcharging is prevented, and the use safety and life of the lithium-ion battery are ensured.

In this embodiment, as shown in Figure 4, according to the function verification simulation results of the linear shunt circuit for equalization charging and overcharge protection, it can be known that:

The normal charging voltage range of a lithium-ion battery cell is 4V-4.05V. The required shunt circuit works when the charging voltage is greater than 4.05V. The resistance settings of the voltage sampling resistor R1 and the voltage sampling resistor R2 should meet: R2/(R1+R2 )=2.5/4.05, after debugging, set the resistance values of voltage sampling resistor R1 and voltage sampling resistor R2 to 30kΩ and 51.5kΩ; the required maximum shunt current is 50mA, and the resistance value of current limiting resistor R3 should meet [4.2-(4.2 -4.05)*2.5/4.05]/R3＝50mA, after debugging, set the resistance value of the current limiting resistor R3 to 70Ω; when the required charging voltage changes from 4.05V-4.2V, the shunt current increases linearly from 0 to 50mA, The resistance value of the negative feedback shunt adjustment resistor R4 should satisfy (4.2-4.05)/R4=50mA. After debugging, the resistance value of the negative feedback shunt adjustment resistor R4 is set to 1.5Ω. The simulation results are: at 4.05V, the linear shunt current is 0A; at 4.2V, the linear shunt current reaches 46mA, and the shunt current changes linearly during the period; after 4.2V, the current limiting resistor R3 begins to limit the current, and the shunt capacity drops sharply.

Wherein, the linear shunt current I _b and the maximum shunt current value I _max satisfy the following expressions:

On the basis of the above-mentioned embodiments, as shown in Fig. 5, the present invention also discloses a lithium-ion battery pack, including: a charging current source, N (N≥2) lithium-ion battery cells, and N-way equalization charging and overcharging Protected linear shunt circuit; among them, N lithium-ion battery cells are connected in series between the positive and negative electrodes of the charging current source; one lithium-ion battery cell is connected in parallel to a linear shunt circuit for equal charging and overcharge protection . That is, each lithium-ion battery cell is equipped with a linear shunt circuit for equalizing charging and overcharging protection, as a charging unit. During charging, the charging current flowing through each charging unit is the charging current provided by the charging current source and is equal. Under normal circumstances, the charging voltage of each charging unit is kept below the current limiting threshold, and there is no shunting process, so the charging current and charging voltage of each lithium-ion battery cell remain consistent. When the charging voltage of any one of the charging units rises abnormally, the shunt circuit in the charging unit starts to work, reducing the charging current flowing through the lithium-ion battery cells in the charging unit and limiting the charging of the charging unit. The voltage continues to increase, playing a role in balance.

Preferably, the linear shunt circuit for balanced charging and overcharge protection may specifically include: voltage sampling resistor R1, voltage sampling resistor R2, current limiting resistor R3, negative feedback shunt adjustment resistor R4 and precision adjustable reference circuit N1; voltage sampling resistor R1 and voltage sampling resistor R2 are connected in series, and the series connected voltage sampling resistor R1 and voltage sampling resistor R2 are connected in parallel between the positive and negative poles of lithium-ion battery cells; current limiting resistor R3, negative feedback shunt adjusting resistor R4 and precision adjustable The reference circuit N1 is connected in series, and the current-limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 are connected in parallel between the positive and negative electrodes of the lithium-ion storage battery; the reference lead of the precision adjustable reference circuit N1 The pin R is connected to the series voltage dividing point of the voltage sampling resistor R1 and the voltage sampling resistor R2, the cathode pin K is connected to the current limiting resistor R3, and the anode pin A is connected to the negative feedback shunt adjusting resistor R4. It should be noted that the linear shunt circuits for equalizing charging and overcharging protection are the same as those described above, so the description is relatively simple, and for relevant details, please refer to the descriptions of the foregoing embodiments.

Preferably, the capacity of the lithium-ion battery pack is not greater than 10Ah.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The above description is only the best specific implementation mode of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of changes or modifications within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention.

The content that is not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims (10)

1. A linear shunt circuit for balanced charging and overcharge protection, comprising: voltage sampling resistor R1, voltage sampling resistor R2, current limiting resistor R3, negative feedback shunt adjusting resistor R4 and precision adjustable reference circuit N1; The voltage sampling resistor R1 and the voltage sampling resistor R2 are connected in series, and the voltage sampling resistor R1 and the voltage sampling resistor R2 connected in series are connected in parallel between the positive and negative poles of the lithium-ion battery cell; The current limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 are connected in series, and the series connected current limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 are connected in parallel to the lithium-ion battery cell Between positive and negative poles; The reference pin R of the precision adjustable reference circuit N1 is connected to the series voltage dividing point of the voltage sampling resistor R1 and the voltage sampling resistor R2, the cathode pin K is connected to the current limiting resistor R3, and the anode pin A is connected to the negative feedback shunt adjustment resistor R4 connect. 2. The linear shunt circuit for balanced charging and overcharge protection according to claim 1, characterized in that the voltage sampling resistor R1 and the voltage sampling resistor are connected in series with the positive and negative poles of the lithium-ion battery monomer for collecting The charging voltage U ₀ of the lithium-ion battery cell, after the charging voltage is divided in series by the voltage sampling resistor R1 and the voltage sampling resistor R2, is used as the input voltage U ₁ of the reference pin R of the precision adjustable reference circuit N1. 3. The linear shunt circuit for balanced charging and overcharge protection according to claim 1, characterized in that one end of the current-limiting resistor R3 is connected to the positive pole of the lithium-ion battery cell, and the other end is connected to the precision adjustable reference circuit N1 The cathode pin K is connected to limit the maximum current that the linear shunt circuit can flow for over-current protection and over-shunt protection. 4. The linear shunt circuit for balanced charging and overcharge protection according to claim 1, characterized in that one end of the negative feedback shunt adjustment resistor R4 is connected to the negative pole of the lithium-ion battery cell, and the other end is connected to the precision adjustable reference circuit The anode pin A of N1 is connected to provide a negative feedback loop of the linear shunt circuit to realize the linear shunt characteristic when the charging voltage of the lithium-ion battery cell is increased. 5. The linear shunt circuit for balanced charging and overcharge protection according to claim 2, wherein the resistance values of the voltage sampling resistor R1 and the voltage sampling resistor R2 meet the following requirements: By setting the resistance values of the voltage sampling resistor R1 and the voltage sampling resistor R2, when the charging voltage _U0 of the lithium-ion battery cell reaches the preset shunt voltage threshold U _threshold , there is: the reference pin R of the precision adjustable reference circuit N1 The input voltage U1 _is equal to the internal reference voltage Ubase _of the precision adjustable reference circuit N1, and the linear shunt current _Ib =1mA. 6. The linear shunt circuit for balanced charging and overcharge protection according to claim 5, characterized in that the precision adjustable reference circuit N1 includes: an internal reference voltage source, an internal integrated operational amplifier, an internal integrated triode and two internal Integrated diodes; among them, the internal reference voltage source is used to provide an internal reference voltage of 2.5V; the internal integrated operational amplifier, internal integrated triode and two internal integrated diodes are used to realize deep negative feedback and adjust the linear shunt current I _b . 7. The linear shunt circuit for balanced charging and overcharge protection according to claim 1, wherein the resistance of the current limiting resistor R3 meets the following requirements: By setting the resistance value of the current limiting resistor R3, the maximum value of the linear shunt current I _b can be adjusted to satisfy: (1+10%)I _max ; where, I _max represents the maximum shunt current value required by the task. 8. The linear shunt circuit for balanced charging and overcharge protection according to claim 1, wherein the resistance value of the negative feedback shunt adjusting resistor R4 meets the following requirements: By setting the resistance value of the negative feedback shunt adjustment resistor R4, the slope of the linear shunt current I _b satisfies a linear change. 9. A lithium-ion battery pack, characterized in that it comprises: a charging current source, an N-section lithium-ion battery cell, and a linear shunt circuit for N-way equalized charging and overcharge protection; wherein, the N-section lithium-ion battery cells are connected in series Afterwards, it is connected between the positive and negative poles of the charging current source; a lithium-ion battery cell is connected in parallel to a linear shunt circuit for equal charging and overcharge protection; N≥2; Linear shunt circuit for balanced charging and overcharge protection, including: voltage sampling resistor R1, voltage sampling resistor R2, current limiting resistor R3, negative feedback shunt adjusting resistor R4 and precision adjustable reference circuit N1; where, voltage sampling resistor R1 and voltage The sampling resistor R2 is connected in series, and the series connected voltage sampling resistor R1 and voltage sampling resistor R2 are connected in parallel between the positive and negative electrodes of the lithium-ion battery cell; the current limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 connected in series, the current-limiting resistor R3, the negative feedback shunt adjusting resistor R4 and the precision adjustable reference circuit N1 are connected in parallel between the positive and negative poles of the lithium-ion battery cell; the reference pin R of the precision adjustable reference circuit N1 is connected to The series voltage dividing point of the voltage sampling resistor R1 and the voltage sampling resistor R2 is connected, the cathode pin K is connected to the current limiting resistor R3, and the anode pin A is connected to the negative feedback shunt adjusting resistor R4. 10. The lithium-ion storage battery pack according to claim 9, wherein the capacity of the lithium-ion storage battery pack is not greater than 10Ah.